1992 blazer 4.3 2wd; when the truck sits over night or for just a few hours i have to crank it for awhile to start and i all most have to force it to start. But when the truck sits for about ten minutes it starts right up. Also when im stopped the truck surges after about 1min of being stopped. so far i replaced plugs,cap rotor, i just put high flow cat and exhaust, also clean egr valve and fuel filter. someone please help!!!!! im lost

"The Idle Air Control valve controls engine idle speed. The IAC motor reacts to voltage pulses from the ECM to move the pintle a given distance in and out for each pulse. The is movement controls air flow around the throttle plate, in turn determining engine idle speed while the engine is in operation."

I myself have had to replace a defective IAC valve which didn't affect the starting whatsoever. All it did was cause and erratic and unstable idle that sometimes would lock out at 1200rpm.

What acts like an electronic choke for the 4.3L is the coolant temperature sensor which when reading a cold coolant temperature, richens up the fuel mixture while the coolant is cold. When it warm up, it sends a signal to the computer to lean out the mixture for normal operation.

What this gentleman is having is a fuel problem where his fuel pressure bleeds off due to a fuel line leak or a defective check valve allowing the fuel to bleed back into the tank. This in turn causes the several seconds of cranking to regain the lost fuel pressure in the main line.

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